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java.lang.Objectorg.apache.commons.collections4.comparators.ComparableComparator<E>
public class ComparableComparator<E extends Comparable<? super E>>
A Comparator
that compares Comparable
objects.
This Comparator is useful, for example, for enforcing the natural order in
custom implementations of SortedSet
and SortedMap
.
Note: In the 2.0 and 2.1 releases of Commons Collections, this class would
throw a ClassCastException
if either of the arguments to
compare
were null
, not
Comparable
, or for which
compareTo
gave inconsistent results.
This is no longer the case. See compare
for
details.
Collections.reverseOrder()
,
Serialized FormField Summary | |
---|---|
static ComparableComparator<?> |
INSTANCE
The singleton instance. |
Constructor Summary | |
---|---|
ComparableComparator()
Constructor whose use should be avoided. |
Method Summary | ||
---|---|---|
static
|
comparableComparator()
Gets the singleton instance of a ComparableComparator. |
|
int |
compare(E obj1,
E obj2)
Compare the two Comparable arguments. |
|
boolean |
equals(Object object)
Returns true iff that Object is is a Comparator
whose ordering is known to be equivalent to mine. |
|
int |
hashCode()
Implement a hash code for this comparator that is consistent with equals . |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
public static final ComparableComparator<?> INSTANCE
Constructor Detail |
---|
public ComparableComparator()
Please use the comparableComparator()
method whenever possible.
Method Detail |
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public static <E extends Comparable<? super E>> ComparableComparator<E> comparableComparator()
Developers are encouraged to use the comparator returned from this method instead of constructing a new instance to reduce allocation and GC overhead when multiple comparable comparators may be used in the same VM.
E
- the element type
public int compare(E obj1, E obj2)
Comparable
arguments.
This method is equivalent to:
((Comparable)obj1).compareTo(obj2)
compare
in interface Comparator<E extends Comparable<? super E>>
obj1
- the first object to compareobj2
- the second object to compare
NullPointerException
- if obj1 is null
,
or when ((Comparable)obj1).compareTo(obj2)
does
ClassCastException
- if obj1 is not a Comparable
,
or when ((Comparable)obj1).compareTo(obj2)
doespublic int hashCode()
equals
.
hashCode
in class Object
public boolean equals(Object object)
true
iff that Object is is a Comparator
whose ordering is known to be equivalent to mine.
This implementation returns true
iff
object.
equals
getClass()
this.getClass()
. Subclasses may want to override this behavior to remain
consistent with the Comparator.equals(Object)
contract.
equals
in interface Comparator<E extends Comparable<? super E>>
equals
in class Object
object
- the object to compare with
true
if equal
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